This book seeks to educate readers about the depth of the ecological crises that our world currently faces, particularly the interrelated issues of global warming and human overpopulation. It also explores the resources available in the Christian tradition for constructive responses to these problems.
In the opening chapter the author provocatively asserts that “those of us whose lives have spanned the seven decades from the beginning of the Second World War will be among the most despised and cursed generations in the whole history of humankind.”  The reason for this is that these generations have destroyed much of the beauty and complexity of the natural world and have created conditions in which the very survival of the human race, or at least human civilization, is profoundly in doubt. Such exploitation of the natural world, Collins argues, constitutes a “profoundly sinful situation.” 
The author provides in the second chapter an overview of some of the current and anticipated future impacts of global warming, such as increases in extreme weather, sea level rise, drought, and melting in the Arctic (though it should be noted that other important negative consequences, such as the spread of disease, the likely increase in violent conflict, and others go unmentioned.) Collins highlights the concern of many scientists that tipping points may soon be reached, or may have already been reached, that will lead to runaway global warming that could endanger the very survival of the human species or bring about the collapse of human civilization and a new Dark Ages. The most essential element of a constructive response to these dire realities, Collins argues, is to “convince people that we are facing a massive, overarching moral problem, bigger than war, far more serious than financial meltdowns, closely linked to but transcending even social inequity, and certainly far outweighing our personal needs and preoccupations.” [51-2]
Rejecting claims that Christianity has been primarily responsible for the ecological crisis, Collins highlights instead problems such as consumerism, individualism, and capitalist and Marxist myths of ‘progress’ that have shaped economic and political life in destructive ways. At the same time, he acknowledges various problems in the Christian tradition that need to be overcome, such as a frequent dualism that devalues nature, certain understandings of ‘dominion’ that he argues are present in the biblical text (though many biblical scholars would challenge Collins’ interpretation), and the inability of many churches to respond in what Collins would consider to be constructive ways to the problem of human overpopulation.
While viewing the Bible as having some potential for the shaping of a positive environmental ethic, Collins finds more insight in the work of numerous contemporary Christian environmental theologians (or 'geologians') such as Thomas Berry, Matthew Fox, Sean McDonagh, Jurgen Moltmann, and various process theologians, who are discussed in the latter part of the book. Collins stresses the need for 'radical shifts of emphasis' in Christian theology. In particular he highlights the need for rethinking our understanding of God, God’s 'transcendence,' and revelation, wanting to emphatically affirm that humans “are just as likely to encounter the transcendent presence of God in the natural world as in the Bible or the church.”  Collins shares his own mystical experience of God through nature that took place at Lake Pedder in southwest Tasmania in 1971, an experience that has deeply influenced the rest of his life. [223-5]
While focusing more on experience, especially experience of nature, and less on the Bible as the locus of revelation (though not denying to the Bible a revelatory role), Collins’ approach also to some extent displaces Jesus from the center of Christian theology. “I am far more preoccupied with the search for God in the world,” he asserts, “than I am with the quest for Jesus.”  He views Jesus “not so much as the central point of history, but as the ultimate symbol that God takes God’s material, natural world utterly seriously.” [260-1] This affirmation of the natural world, he argues, is a primary meaning of the Incarnation.
In surveying the state of our world, does Collins have hope for the future? As a historian, he views it as very unlikely that the radical changes that are needed to prevent the collapse of human civilization will take place. Nevertheless, he says, “the last thing I want to encourage is cynicism. We have to do as much as is humanly possible.”  As a person of faith, he stresses the need to trust God’s providence. “My trust,” he says, “is in a Creator God who will not abandon the world, which is a product of divine creativity.”  The precise manner in which God will save the world, however, he does not claim to know.
Overall, this book presents much helpful information on the current imperiled state of our world, though fuller and clearer introductions to climate change exist. As to the theological dimension of the book, many Christian readers will likely find it to be insufficiently orthodox, particularly with regard to Collins’ understanding of the person of Jesus. Nonetheless, the author’s challenge to the churches to take far more seriously the depth of our current ecological/civilizational crises, and to better appreciate the importance of nature as a context for the experience of God, are certainly calls that must be heeded and responded to. And for the author’s efforts to raise awareness of these issues we should be profoundly grateful.